The patch titled
Subject: mm, thp: fix migration of PTE-mapped transparent huge pages
has been added to the -mm tree. Its filename is
mm-thp-fix-migration-of-pte-mapped-transparent-huge-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-fix-migration-of-pte-mapped-transparent-huge-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-fix-migration-of-pte-mapped-transparent-huge-pages.patch
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From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: mm, thp: fix migration of PTE-mapped transparent huge pages
We don't have native support of THP migration, so we have to split huge
page into small pages in order to migrate it to different node. This
includes PTE-mapped huge pages.
I made mistake in refcounting patchset: we don't actually split PTE-mapped
huge page in queue_pages_pte_range(), if we step on head page.
The result is that the head page is queued for migration, but none of tail
pages: putting head page on queue takes pin on the page and any subsequent
attempts of split_huge_pages() would fail and we skip queuing tail pages.
unmap_and_move_huge_page() will eventually split the huge pages, but only
one of 512 pages would get migrated.
Let's fix the situation.
Fixes: 248db92da13f2507 ("migrate_pages: try to split pages on queuing")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/mempolicy.c~mm-thp-fix-migration-of-pte-mapped-transparent-huge-pages mm/mempolicy.c
--- a/mm/mempolicy.c~mm-thp-fix-migration-of-pte-mapped-transparent-huge-pages
+++ a/mm/mempolicy.c
@@ -532,7 +532,7 @@ retry:
nid = page_to_nid(page);
if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
continue;
- if (PageTail(page) && PageAnon(page)) {
+ if (PageTransCompound(page) && PageAnon(page)) {
get_page(page);
pte_unmap_unlock(pte, ptl);
lock_page(page);
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-thp-fix-migration-of-pte-mapped-transparent-huge-pages.patch
thp-cleanup-split_huge_page.patch
thp-vmstats-count-deferred-split-events.patch
mm-tracing-refresh-__def_vmaflag_names.patch
mm-cleanup-pte_alloc-interfaces.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-2.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-3.patch
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